Jeong-Euy Park

Replication of the association between a chromosome 9p21 polymorphism and coronary artery disease in Japanese and Korean populations

AbstractCoronary artery disease (CAD) has become a major health problem in many countries. Recent genome-wide association studies have identified the association between rs1333049 on chromosome 9p21 and susceptibility to CAD in Caucasoid populations. In this study, we evaluated the associations of rs1333049 with CAD in Japanese (604 patients and 1,151 controls) and Koreans (679 patients and 706 controls). We found a significant association in both Japanese [odds ratio (OR) = 1.30, 95% confidence interval (CI); 1.13–1.49, p = 0.00027, allele count model] and Koreans (OR = 1.19, 95% CI; 1.02–1.38, p = 0.025, allele count model). These observations demonstrated that chromosome 9p21 was the susceptibility locus for CAD also in East Asians.

Trichostatin A Exacerbates Atherosclerosis in Low Density Lipoprotein Receptor–Deficient Mice

Objective—Histone acetylation has been shown to be involved in expression of a restricted set of cellular genes including various proinflammatory molecules. We aimed to investigate the relationship between histone acetylation and atherosclerosis. Methods and Results—In low-density lipoprotein (LDL) receptor-deficient (Ldlr−/−) mice fed an atherogenic diet for 4 or 8 weeks, trichostatin A (TSA), a specific histone deacetylase inhibitor, exacerbated atherosclerosis without alteration on plasma lipid profiles. When we assayed the effects of TSA on expressions of oxidized LDL (oxLDL) receptors on RAW264.7 macrophage, we found that TSA increased CD36 mRNA and protein, as well as cell surface expression of CD36. TSA also increased acetylation at the CD36 promoter region. The uptake of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine percholate (Dil)-labeled oxLDL was enhanced in RAW264.7 macrophage by TSA. Furthermore, TSA treatment increased CD36 mRNA expression in aorta, and SRA, tumor necrosis factor (TNF)-&agr;, and vascular cell adhesion molecule-1 (VCAM-1) were also elevated, whereas IL-6 and IL-1&bgr; expressions were decreased. Conclusions—Our findings suggest that histone acetylation could play some role in atherogenesis by modulating expressions of oxLDL receptor and some proatherogenic genes. Therefore, our results indicate that increased histone acetylation may affect the progress of atherosclerosis.

Glucocorticoid-induced tumour necrosis factor receptor family related protein (GITR) mediates inflammatory activation of macrophages that can destabilize atherosclerotic plaques

Glucocorticoid‐induced tumour necrosis factor receptor family related protein (GITR) is the 18th member of the tumour necrosis factor receptor superfamily (TNFRSF18) and is known to interact with its cognate ligand GITRL (TNFSF18). We investigated the potential role of GITR in the pro‐inflammatory activation of macrophages. Immunohistochemistry and in situ hybridization analyses of human atherosclerotic plaques demonstrated that GITR and its ligand are expressed mainly in lipid‐rich macrophages. We then investigated the role of GITR in human and mouse monocyte/macrophage functions. Stimulation of GITR caused nuclear factor (NF)‐κB‐dependent activation of matrix metalloproteinase‐9 (MMP‐9) and pro‐inflammatory cytokine expression in both the human and mouse monocytic/macrophage cell lines, THP‐1 and RAW264.7, respectively. These cellular responses were also observed when the THP‐1 cells were treated with phorbol‐12 myristate‐13 acetate (PMA), which is known to induce macrophage differentiation. To demonstrate that these responses are not restricted to cultured cell lines, we tested primary macrophages. Both peritoneal and bone marrow‐derived macrophages responded to GITR stimulation with induction of MMP‐9 and tumour necrosis factor‐α (TNF‐α). Furthermore, the GITR staining pattern overlapped with those of MMP‐9 and TNF‐α in atherosclerotic plaques. These data indicate that GITR‐mediated macrophage activation may promote atherogenesis via the induction of pro‐atherogenic cytokines/chemokines, and destabilize the atherosclerotic plaques via the induction of the matrix‐degrading enzyme, MMP‐9.

CD40L Activation in Circulating Platelets in Patients with Acute Coronary Syndrome

The CD40-CD40L interaction, which was initially shown to have important roles in the T cell-mediated activation of B cells during humoral immune responses, is now known to have roles in activation of endothelial cells, smooth muscle cells, and macrophages within atherosclerotic plaques. Recently, CD40L expression was found in activated platelets in the thrombus in vivo and CD40L was reported to be responsible for the platelet-mediated activation of endothelial cells in vitro. To investigate the activation status of platelets in coronary artery disease patients, we tested expression levels of CD40L, and platelet-endothelial cell adhesion molecule-1 (PECAM-1/CD31) in platelets isolated from peripheral blood, using flow cytometric analysis. Twenty-nine patients with acute coronary syndrome (10 acute myocardial infarction and 19 unstable angina patients) were compared with 14 normal subjects or 14 stable angina patients. In platelets isolated from normal subjects, the expression of CD40L was not detected in all subjects. In the patients with acute coronary syndrome, the average level of CD40L showed a significant increase (p = 0.0028), while stable angina patients did not have any increase when compared to normal subjects. Patients with more complex lesions or vessel occlusion tended to have a high platelet CD40L level compared to patients who do not. The expression levels of CD31 were increased in a small portion of the ACS patients. These data indicate that the rupture of plaque and subsequent formation of thrombus may lead to the activation of CD40L expression in circulating platelets of ACS patients.

Z39Ig is expressed on macrophages and may mediate inflammatory reactions in arthritis and atherosclerosis

Z39Ig is a transmembrane protein containing two Ig homology domains with unknown functions. Immunohistochemical analyses of human carotid atherosclerotic plaques detected Z39Ig staining in areas rich in foamy macrophages. Z39Ig staining was also observed in macrophages in the lining layers and sublining areas of rheumatoid arthritis synovium. Z39Ig staining in the osteoarthritis synovium was restricted to macrophages in the lining layers. To identify the role(s) of Z39Ig in the function of macrophages, we used human monocytic cell lines TF‐1A (Z39Ig‐negative) and THP‐1 (Z39Ig‐positive). The expression of Z39Ig was induced in TF‐1A cells, when they were differentiated into macrophages by treatment with PMA. The stimulation of PMA‐treated TF‐1A or THP‐1 cells with immobilized anti‐Z39Ig mAb induced the secretion of IL‐8 and matrix metalloproteinase (MMP)‐9, which was dependent on NF‐κB activation. These data indicate that the macrophage Z39Ig is involved in the pathogenesis of inflammatory diseases through chemokine induction, which will promote the migration of inflammatory cells into the lesion area, and MMP‐9 induction, which will contribute to cartilage destruction or extracellular matrix degradation.

Activation of monocytes, T-lymphocytes and plasma inflammatory markers in angina patients.

Inflammation and activation of immune cells have important roles in the pathogenesis of atherosclerosis. We analyzed the plasma levels of inflammatory markers and the degree of activation of peripheral blood monocytes and T-lymphocytes isolated from 12 unstable angina, 12 stable angina, and 12 normal subjects. In 20%-33% of patients, monocytes expressed high basal levels of IL-8, tissue factor, IL-1β, and monocyte chemoattractant protein-1 mRNA. Furthermore, basal mRNA levels of these cytokines showed strong correlation with each other (p < 0.01 in all combination) but not with tumor necrosis factor-α or transforming growth factor-β1. Plasma level of C-reactive protein was highest in the unstable angina patients (1.63±0.70 mg/l) and lowest in the control subjects (0.22±0.08 mg/l) (P = 0.03). We also observed a high correlation between C-reactive protein level and the occurrence of minor and major coronary events during 6 months of follow-up. Activation status of T-cells, assessed by the percentage of HLA-DR positive cells, was highest in the unstable angina patients (26.8±1.4%) compared with that in the control (14.7±1.2%) (P = 0.0053). Our data represent the first case showing that the circulating monocytes in angina patients are activated to a state express numerous proatherogenic cytokines. These results may help to diagnose angina patients according to the inflammatory markers and evaluate the prognosis of the disease.

Efficacy of Xience/promus versus Cypher in rEducing Late Loss after stENTing (EXCELLENT) trial: Study design and rationale of a Korean multicenter prospective randomized trial

BACKGROUNDnThe everolimus-eluting stent (EES) is a newly developed drug-eluting stent using the MULTILINK VISION stent platform combined with the drug everolimus contained in a polymer coating. Recently reported randomized trials have shown the noninferiority and subsequent superiority of the EES compared with the paclitaxel-eluting stent regarding in-stent late loss (LL) at 180 days. However, there have been no studies comparing head to head the EES with the sirolimus-eluting stent (SES), which has shown the least amount of LL among the previously released drug-eluting stent (DES). In addition, adjunctive antiplatelet therapy is a critical factor in optimizing long-term DES safety. Despite the recommendation of the American Heart Association/American College of Cardiology to maintain 12 months of dual antiplatelet therapy, there have been no prospective randomized trials comparing the efficacy and safety of different durations.nnnSTUDY DESIGNnIn the Efficacy of Xience/promus versus Cypher in rEducing Late Loss after stENTing (EXCELLENT) trial, approximately 1,400 patients are being prospectively and randomly assigned in a 2 x 2 factorial design according to the type of stent (EES vs SES) and the duration of dual antiplatelet therapy (6 vs 12 months). The primary end point is in-segment LL at 9 months for comparison of type of stent, and the coprimary end point is target vessel failure at 12 months for comparison of dual antiplatelet therapy duration.nnnSUMMARYnThe EXCELLENT trial is the largest study yet performed to directly compare the efficacy and safety of the EES versus the SES. In addition, this study will also address the issue of a 6- versus 12-month duration of dual antiplatelet therapy for post-percutaneous coronary intervention management.

Early expression of a malignant phenotype of familial hypertrophic cardiomyopathy associated with a Gly716Arg myosin heavy chain mutation in a Korean family

The clinical course and prognosis of familial hypertrophic cardiomyopathy (HCM) are different according to the type of mutation in the genes for sarcomere proteins. It has been disputed that a mutation, which occurs at a functionally important region in the sarcomere proteins, may increase the penetrance and expressivity of the disease. We searched for a causative mutation in an HCM family, which is characterized by early expression of clinical phenotype, high incidence of sudden death at young ages, and progressive heart failure in adults. Among the 32 family members in 4 generations, 13 were affected; 4 died suddenly before age 16, 2 children have already had full expression of the cardiac hypertrophy, and other adults have either progressive heart failure or poor left ventricular systolic functions. PCR-SSCP (polymerase chain reaction-single strand confirmation polymorphism) analysis of genomic DNAs isolated from peripheral blood leukocytes of the family members identified a Gly716Arg mutation in the cardiac beta-myosin heavy chain gene, which was cosegregated with the clinical phenotype. The mutation is localized near a functionally important site of the myosin heavy chain, the 2 active thiols, which contribute to the adenosine triphosphatase activity of myosin S1. This family provides further evidence that the mutation, which occurs at a functionally important site of the myosin heavy chain, is associated with the high penetrance and early expression of HCM.

A novel chemokine, Leukotactin-1, induces chemotaxis, pro-atherogenic cytokines, and tissue factor expression in atherosclerosis

Chemokines such as monocyte chemoattractant protein (MCP) -1 and interleukin (IL)-8 are known to be involved in various processes in atherosclerosis such as plaque formation, plaque rupture, and thrombus formation. We investigated whether a new chemokine, Leukotactin (LKN)-1, is involved in atherosclerosis. We tested the expression of LKN-1 by immunohistochemical methods in carotid atherosclerotic plaque specimen. Induction of pro-inflammatory cytokines, transmigration, and tissue factor (TF) expression were tested in THP-1 cells and human peripheral blood monocytes treated with recombinant human LKN-1. Immunohistochemical analyses revealed that expression of LKN-1 occurs in regions of plaques rich in foam cells. In a Boyden chamber assay, THP-1 cells treated with 0.01--10 nM of LKN-1 transmigrated through gelatin coated filters in a dose dependent manner. LKN-1 also induced the transient expression of TNF-alpha, IL-8, and MCP-1 within 15 min of the treatment of the THP-1 cells. When peripheral blood monocytes were treated with LKN-1, expression levels of TF and TF-mediated procoagulating activity were induced in a time- and dose-dependent manner. These results raise the possibility that LKN-1 is another chemokine that is involved in the atherogenesis. LKN-1 may chemoattract immune cells into the plaque, induce pro-inflammatory cytokines, and produce thrombi by inducing TF expression.

Genetic factors associated with endothelial dysfunction affect the early onset of coronary artery disease in Korean males.

The maintenance of balance between nitric oxide (NO) and the superoxide anion is required for proper functioning of the endothelium. To investigate the relationship between genetic factors associated with endothelial function and the development of coronary artery disease (CAD), endothelial nitric oxide synthase (ecNOS) gene a/b polymorphism and NADH/NADPH oxidase p22 phox gene C242T polymorphism were examined in 305 Korean male CAD patients and 215 healthy male control subjects. The β-fibrinogen gene H1/H2 polymorphism was also analyzed. Both ecNOS a/b and p22 phox C242T polymorphisms were found to be associated with the development of CAD in the study population (p = 0.020 and 0.011, respectively). When the association was analyzed by age, statistical significance was retained only in those <51 years (p = 0.021 and 0.025 for the a/b and the C242T polymorphism, respectively) and not in those >51 years of age (p =0.155 and 0.278 respectively). However, the distribution of the β-fibrinogen H1/H2 genotypes was not found to be associated with the development of CAD in either the ≤50 (p = 0.611) or >50 groups (p = 0.188). The ecNOS gene a/b polymorphism and the NADH/NADPH oxidase p22 phox gene C242T polymorphism were found to be significantly associated with the development of CAD in Korean male patients less than 51 years old.